1. Field of the Invention
The present invention relates to tethered aerostats; and more particularly, to an improved mooring structure for maintaining the aerostat at the desired height in flight, to inhaul and outhaul its tether for launching and retrieving, and to provide a conductive path from a source of power to the aerostat.
2. Description of the Prior Art
The term "aerostat" as used herein refers to an inflatable, lighter than air structure that is preferably helium filled and capable of elevating and supporting communications equipment above the earth's surface. To provide the proper aerodynamics in elevating and maintaining such elevations, a typical aerostat has a dirigible-like configuration with a nose portion and stabilizing fins adjacent its tail.
Large aerostats have been in use for several years for the purpose of elevating communications equipment to altitudes in the order of 3000 to 4500 meters. Such aerostats are extremely useful for the purposes intended, but generally tend to be complex, expensive, and require an elaborate ground support system. There are many applications and missions where the elevation of an aerostat to approximately 750 meters above the earth's surface is adequate. For example, such elevation is satisfactory for increasing the range of radar border surveillance equipment, or as an aerostat platform for voice and data relay functions, where the communication range is in the neighborhood of 100 kilometers in radius, or as a communication relay between ground control stations and remotely piloted vehicles, or even for a rural telephone transponder where telecommunications requirements are limited and potential telephone subscribers are considerably spread out. One small aerostat platform operating at an altitude of 750 meters, for example, could provide telephone service via low cost radio units to subscribers as far as 110 kilometers from the aerostat.
To use a conventional large aerostat for such applications is unnecessarily expensive including the cost of the ground handling equipment as well as the inherent limitation of a non-mobile system. Even by reducing the overall size of such aerostats, the available apparatus for mooring, inhauling and outhauling still involve a similar degree of complexity.
Therefore, it is desirable to provide tethered aerostat apparatus that has all of the advantages of the conventional aerostat, with the exception of altitude but which is less expensive to manufacture, locate, and operate. Such tethered aerostat system should be adaptable to a wide range of missions and provide flexibility of operation at a cost much less than the conventional systems.